This invention generally relates to motor vehicle wheel assemblies and, more particularly, to the inboard retention of a wheel bearing used for rotatably mounting a live spindle in the wheel assembly.
Vehicle wheel assemblies utilizing live spindles are found in motor vehicles capable of functioning in an four-wheel drive operational mode. The live spindle or hub is journaled or mounted for rotation within a mounting component of the wheel assembly. A wheel bearing is interposed between the mounting portion and the spindle enabling the spindle to rotate relative to the mounting portion. An axle shaft is rigidly connected to the live spindle and includes an inboard flange for retaining the bearing on the live spindle. If the vehicle is configured to operate in either a two-wheel or four-wheel drive mode, a center axle disconnect mechanism is provided to selectively couple the axle to the transmission.
Motor vehicle wheel assemblies utilizing dead spindles are also capable of operating in either two-wheel or four-wheel drive modes. A hub lock is provided to selectively couple the wheel assembly to the axle. The axle shaft typically extends through a central bore in the dead spindle and is journaled therein by a set of needle bearings or another type of bearing. Generally, the dead spindle is threaded on its outboard end and has an inboard flange which operates as the inboard retainer for the wheel bearing on the spindle. A nut is threaded onto the threaded end of the dead spindle and is torqued or tightened down to sufficiently pre-load the wheel bearing and the assembled components. This cooperation maintains the hub on the dead spindle while enabling relative rotation between these two components.
Today, types of hub locks are in common use on dead spindles. They include manually actuated hub locks and self-locking hub locks. In either variety, the hub is allowed to free wheel relative to the axle in the two-wheel drive mode and is rigidly connected to the axle for rotation therewith in the four-wheel drive mode. Manual hub locks are most often mounted to couple the outboard end of the hub to the outboard end of the axle. During operation, if locked, the drive axle and the hub, as well as the wheel mounted to the hub, will rotate together. When unlocked, the hub is free to rotate independently of the axle thereby allowing the transfer case to disengage the axle from the transmission and providing the vehicle with better fuel mileage.
Prior art designs are limited in that the outboard mounting of the hub lock protrudes a substantial distance from the hub flange if an outboard retainer is used. Inboard retention of the hub and the bearing has significant size constraints because of the packaging of the suspension king pin axis, the axle joints and, if provided on the vehicle, the anti-lock brake system components.
With the above limitations in mind, it is an object of the present invention to provide a live spindle with hub lock and inboard bearing retention while separating the bearing retention function from the axle. In doing so, the present invention seeks to permit a limited amount of axial movement in the axle without affecting the pre-load of the wheel bearing. Axial movement of the axle may be a necessary result of the specific suspension of the vehicle as well as the steering component of the wheel assembly.
Another object of this invention is to provide inboard bearing retention while minimizing the size of the packaging for the bearing retainer. Still another object of this invention is to provide a locking feature which will assure that the bearing retainer does not inadvertently become disengaged from the live spindle during operation of the vehicle and yet simplify the construction necessary for inboard bearing retention.
In overcoming the limitations of the prior art and achieving the objects mentioned above, the present invention provides a live spindle mounted for rotation in a mounting portion of the wheel assembly. The live spindle includes a central bore through which extends an axle that can be driven in rotation by the vehicle's transmission. A hub lock is used to couple the outboard end of the live spindle to the outboard end of the axle so that rotation of the axle will drive the live spindle and the attached wheel thereby operating the vehicle in its four-wheel drive mode. The live spindle is rotatably supported within the knuckle or mounting portion of the vehicle wheel assembly by a wheel bearing whose inner race is seated on the live spindle.
Inboard bearing retention is provided by forming threads on the outer diameter of the live spindle's inboard end. The diameter at which the threads are formed is less than that of the press-fit surface defining the bearing seat on the spindle. A primary feature of the present invention is an inboard bearing retainer or nut which engages with the threads on the live spindle and includes surfaces which define the inboard portion of the bearing seat. This provides the present invention with a small or tight packaging. A radial flange on the bearing retainer engages the inboard end and inner diameter of the bearing inner race and prevents inboard axial movement of the wheel bearing. By progressively threading the bearing retainer onto the live spindle, the proper torque for pre-loading the bearing can be set.
A primary feature of the present invention is a one-piece retainer lock which is press-fit into the inboard end of the live spindle. The particular features of the retainer lock allowing it to perform a variety of functions enabling it to 1) prevent disengagement of the bearing retainer from the live spindle; 2) operate as a bearing for the axle within the live spindle; and 3) receive axial thrust loads without transferring them to the wheel bearing.
Formed on the inboard end of the live spindle are a number of equidistantly spaced and radially directed slots. Radial slots are also formed on the inboard side of the bearing retainer so that, once the minimum bearing pre-load has been established by the bearing retainer, the retainer can be further adjusted to align at least one of its slots with at least one of the slots in the inboard end of the live spindle. The retainer lock is press-fit into engagement with the inboard end of the spindle and bearing retainer so that a locking boss, formed on the retainer lock and bearing, is located within and extending between the aligned slots of the live spindle and bearing retainer. The locking boss prevents the bearing retainer from rotating relative to the live spindle and inadvertently becoming disengaged therefrom.
In the preferred embodiment, the retainer lock includes a portion which defines a sleeve or shaft bearing. The sleeve bearing extends along an inner surface of the live spindle and supports the axle therein.
The inboard end of the retainer lock includes a radial portion defining a thrust face which extends axially inboard beyond the bearing retainer. The thrust face is a rubbing surface which receives axial loads resulting from end play in the axle and the various other components of the wheel assembly. This prevents the loads from being transferred directly to the wheel bearing.
In an alternative embodiment, the sleeve bearing is replaced by a separate and distinct needle bearing of the common variety or, in yet another embodiment, the locking boss is replaced by a separate roll pin. The roll pin is first positioned within the aligned slots of the spindle and the bearing retainer and secured by the retainer lock being press-fit thereover so as to define the thrust washer.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.